Читать книгу Sustainable Nanotechnology - Группа авторов - Страница 48

The surface area increases with the reduction in the size of the same quantity of any material. NPs, although made from nontoxic materials, become hazardous, as the material developed reactivity at molecular level. The toxic effect of few such particles does not seem hazardous, but if more surface area becomes available, it will further add on risk. Thus, surface area also requires attention and monitoring for the toxicity study along with the size. As size reduces, it increases surface area and finally enhances capability to react with oxygen. Due to increased reaction with oxygen, it increases inflammation, fibrosis, cytotoxicity, oxidative injury, and carbon deposition in lungs of mineral particles, quartz, titanium dioxide, asbestos, and carbon black despite the same materials being inert at macro or higher size range[32]. Toxicity in biological systems generated by NPs is predominantly through the formation of oxidative responses and consequent formation of free radicals. Free radicals are hazardous as they oxidize the lipid and damage the DNA with inflammatory responses. The data also shows that the smaller the size, the more able it is toward the formation of reactive oxygen species [20]. Every NP thus closely needs to be monitored for its new developed chemical reactivity, and it should be done from its development phase.